Preparation of a novel porous adsorption material from coal slag and its adsorption properties of phenol from aqueous solution

Abstract

A new porous adsorption material (PAM) was successfully prepared from raw coal slag and characterized by several techniques, including N2 adsorption–desorption isotherm, thermogravimetric analysis (TGA), flourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), Transmission electron microscope (TEM) and X-ray diffraction (XRD) measurement. The preparation procedure of PAM involved two steps: (1) SiO32− chemical leaching from coal slag, and (2) preparation of the PAM. The optimum SiO32− leaching condition was confirmed at 30mL HCl for the pretreated processes, 200mesh particle size of coal slag, leaching temperature of 100°C, reaction time of 2h, NaOH initial concentration of 30wt.%, and the ratio of alkaline to slag of 2:1. Under this condition, SiO32− leaching yield arrived at 39.42wt.%, which accounted for 80.78wt.% of the total content of SiO32 in coal slag. The PAM was then easily prepared with the yield of 99.20wt.% at 90°C for 4h with Ca/Si mole ratio of 0.75:1. According to Langmuir model, the adsorption capability of phenol on the PAM with a maximum uptake was 63.78mg/g. According to adsorption thermodynamic results, the process was exothermic, thermodynamically feasible, spontaneous and chemically controlled.